A 5-year-old boy presented with a 2-day history of acute febrile illness. During evaluation, his blood samples were found to be so lipaemic (figure) that it caused interference in analyte measurements. The child was born of a non-consanguineous marriage, there was no history of failure to thrive or developmental delay, and there were no reports of any previous episodes of acute pancreatitis. Neither xanthomata nor hepatosplenomegaly was found at clinical examination. Laboratory test results found a normal fasting blood glucose concentration (4·5 mmol/L). However, triglycerides were found to be very high at 21·4 mmol/L (normal level &lt;1·7 mmol/L). Total serum cholesterol was 5·5 mmol/L (normal level &lt;5·2 mmol/L), LDL cholesterol by direct measurement was 0·7 mmol/L (normal level &lt;2·6 mmol/L), and HDL cholesterol was 0·5 mmol/L (normal level &gt;1·0 mmol/L). Investigations for secondary causes of hyperlipidaemia were negative. Dilated fundus examination showed creamy white discolouration of retinal blood vessels (figure) suggestive of lipaemia retinalis; no retinal haemorrhages or exudates were seen. Fasting lipid profiles of other family members were normal. Taking into account the young age of the patient, the lipaemic plasma, the hypertriglyceridaemia, the lipaemia retinalis, and the lack of indications that his difficulties were secondary to any other diseases causing hypertriglyceridaemia, the boy was diagnosed with familial chylomicronaemia syndrome (FCS). As treatment is mainly dietary fat restriction, the child was started on a low-fat diet-less than 10% of total calories-with medium-chain triglyceride supplements.Read more here: https://pxmd.co/eIxqY